Researchers have found that the amount of time a blood sample stays in storage can affect test results. The findings have important implications for any future research that uses blood from biobanks. The details are in a paper just published in the journal EBioMedicine.
Biobanks are an important source of blood samples for medical research. Researchers normally account for differences between donors, such as sex, age, and health diagnoses. There may be other important factors to consider, however, and this was the focus of the new study.
Researchers from Uppsala University analyzed 380 blood plasma samples from the Västerbotten Intervention Programme at Umeå University. The samples, collected from 1988 to 2014, were from 106 Swedish women. The donors were between 29 and 73 years of age but the team focused on samples from 50 year old women when studying the effect of storage time. The team gathered data on 108 different blood proteins.
The researchers found that storage time had a significant effect on 18 proteins, explaining 4.8–34.9% of the overall variance. For comparison, donor age accounted for 1.1–33.5% variance. This shows that storage time is just as important as donor age when interpreting test results. The team also found seasonal variance—blood samples taken at different times of the year affected 36 proteins and explained 4.5% of the variance.
These findings are significant because storage time is never taken into account when researchers use biobank blood samples. The amount of time a sample has been frozen, along with the time it was collected, can affect test results just as much as the donor’s age. Since biobanks are commonly relied on for medical research, it’s critical to understand any factors that cause variance. The team recommends that future studies take storage time and seasonal differences into consideration when interpreting results.
Stefan Enroth, Göran Hallmans, Kjell Grankvist, Ulf Gyllensten. Effects of Long-Term Storage Time and Original Sampling Month on Biobank Plasma Protein Concentrations. EBioMedicine (2016).